Move the fences | Science

The high-altitude grasslands of Tibet have become badly degraded, but fencing out key grazers, such as these Tibetan antelopes, is not a long-term solution.

PHOTO: STAFFAN WIDSTRAND / WILD WONDERS OF CHINA

The sensitive alpine meadow and steppe systems of the Tibetan Plateau have experienced serious degradation over the past half-century. To restore these habitats, an extensive system of wire fences has been erected across the region; some have been in place for 30 years. Fences can protect plants from immediate grazing by livestock, but they limit connectivity for other organisms, interrupt trophic dynamics, and artificially divide landscapes. Sun et al. used a large-scale meta-analysis to determine whether these fences have been effective for restoration, how they affect wildlife, and what effect they have on human populations on the basis of interviews with local herdsmen. Fences that had been in place for short to medium periods of time were able to increase aboveground vegetative biomass for both meadows and steppe. However, long-term fencing decreased plant growth and diversity, with negative ecosystem impacts. In addition, fences inhibited the movement of three focal mammal species—Tibetan gazelles, yaks, and donkeys—which increased their grazing impact on unfenced regions. The herders perceived fences as not only preventing their ability to use traditional grazing practices but also as being ineffective overall. Fences can be useful tools but only when they are transitional and impermanent.

Sci. Bull. 10.1016/j.scib.2020.04.035 (2020).



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